This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Motor impairments represent the primary functional deficit observed following stroke. Over 80% of all stroke victims exhibit some form of movement disability with upper extremity impairments being the most common. Post stroke motor rehabilitation can often significantly improve motor function depending on the severity and location of the damage (Duncan et al., 2000). Although the specific neural mechanisms underlying motor recovery are unknown, recent neural imaging and cortical stimulation experiments have implicated functional compensation within residual neural tissue. Rehabilitation induced improvements in motor performance can alter both the pattern of cortical activity associated with movement (Cramer, 2002) and the locus of stimulation evoked movement representations within intact cortical tissue (Nudo et al., 1996;Kleim et al., 2003). Restoration of movement through motor rehabilitation may be supported by functional reorganization within intact motor areas. Understanding those factors contributing to the capacity for motor cortex reorganization will contribute to the development of putative therapeutic interventions for enhancing motor recovery after stroke.